1. Field of the Invention
The invention relates to a data storage device and, in particular, to a data storage device including an interface which is capable of storing a large amount of data such as audio/video data and an interface device used for the data storage device.
2. Description of the Related Art
In the prior art, when audio/video data including image data are stored by using a disk media such as a hard disk, for an effective configuration for storing, real-time consecutive code data generated in encoding audio/video data is required without exception since a the speed of writing data to the disk media is lower than a the speed of inputting the audio/video data.
Specifically, a sequence of thus generated code data is temporarily stored in a high speed buffer memory. Furthermore, also using another buffer memory in a disk device makes it possible to avoid xe2x80x9cbuffer underrunxe2x80x9d.
For example, a device is disclosed in Japanese Laid-Open Publication No. H10-320913 (namely, 320913/1998) as a type of the above prior data storage device.
However, in the above prior data storage device, it is required to prepare a large amount of buffer memory since the buffer memory is loaded with audio/video data encoded. For example, if the encoded data are received by an FIFO memory as the buffer memory, the FIFO memory must have a very large memory capacity. At any rate, the cost to process the audio/video data may be increased due to the large amount of memory.
That is, since the audio/video data are given in real-time and stored in the disk media having low data writing speed, a hardware configuration is required to temporarily keep the audio/video data.
Also, in the prior data storage device, it is difficult for an application, such as a file system performing area management, to perform area management without using a buffer memory.
This is because data should be maintained for a predetermined time not to eliminate the data immediately after writing of the data. For example, the data may be used to rewrite the data into the data storage device when an error occurs in write operation.
Therefore, it is an object of the invention to provide a data storage device which is capable of reducing a cost of the device and developing operation response by eliminating unnecessary buffer memory.
It is also an object of the invention to provide an interface to which a general-purpose area management software can be used even if a buffer memory is deleted.
According to a first aspect of the invention, there in provided a data storage device which comprises a read/write device which writes data to a data storage media and reads the data from the data storage media, an interface device which controls the read/write device for data input/output, and a buffer memory which is controlled by the interface device. Herein, the interface device comprises a memory control device which activates a request signal which requests to transmit the data, receives the data on a data bus when the request signal is activated and an acknowledgement signal is responded to the request signal, stores the data to the buffer memory, and reads the data from the buffer memory and transmits the data to the read/write device, and an operation control device which receives an instruction command from outside, and instructs the memory control device to activate or inactivate the request signal and instructs the memory control device to transmit the data to the read/write device in response to the instruction command.
According to a second aspect of the invention, there is provided an interface device which controls input/output of data to a read/write device reading or writing data to a data storage media. Herein, the interface device comprises a memory control device which activates a request signal which requests to transmit the data, receives the data on a data bus when the request signal is activated and an acknowledgement signal is responded to the request signal, stores the data to the buffer memory, and reads the data from the buffer memory and transmits the data to the read/write device, and an operation control device which receives an instruction command from outside, and instructs the memory control device to activate or inactivate the request signal and instructs the memory control device to transmit the data to the read/write device in response to the instruction command.
According to a third aspect of the invention, there is provided a method of storing data in a data storage device including a read/write device which writes data to a data storage media and reads the data from the data storage media. The method comprises the steps of controlling the read/write device for data input/output, controlling a buffer memory, activating a request signal which requests to transmit the data, receiving the data on a data bus when the request signal is activated and an acknowledgement signal is responded to the request signal, storing the data to the buffer memory, reading the data from the buffer memory and transmitting the data to the read/write device, receiving an instruction command from outside, and instructing to activate or inactivate the request signal and instructing to transmit the data to the read/write device in response to the instruction command.
According to a fourth aspect of the invention, there is provided a recording medium readable by a computer, tangibly embodying a program of instructions executable by the computer to perform a method of storing data in a data storage device including a read/write device which writes data to a data storage media and reads the data from the data storage media. The method comprises the steps of controlling the read/write device for data input/output, controlling a buffer memory, activating a request signal which requests to transmit the data, receiving the data on a data bus when the request signal is activated and an acknowledgement signal is responded to the request signal, storing the data to the buffer memory, reading the data from the buffer memory and transmitting the data to the read/write device, receiving an instruction command from outside, and instructing to activate or inactivate the request signal and instructing to transmit the data to the read/write device in response to the instruction command.